Ultra high frequency oscillator system



April 9, c. HANSELL 2,196,392

ULTRA area FREQUENCY OSCILLATOR SYSTEM Filed Now). 28, 1934 AA/7510144 A3 mW 0'\ 4 OUTPUT FC PEN ELL CLARE E .H .S lllllllllllllll BY ATTORNEYPatented Apr. 9, 1940 UNI-TED STATES.

ULTRA. HIGH. FREQUENCY OSCILLATOR SYSTEM Clarence W. HanselLJPortJefferson, N. Y., as

signor to Radiocorporation of America,

poration of Delaware Application November 28, 1934, Serial No. 755,158"

18 Claims;

This invention relates tohigh frequency oscillation generators.

For the purpose of generating oscillations having frequencies-of theorder of 300,000 kilocycles and: higher, there have commonlybeenusedsuchapparatuses the Barkhausen oscillator'and the magnetron. The.oscillations produced. in these oscillators are obtained/by. a sortofwhistle effect wherein the electrons themselves produce. the

m:- oscillationswithout any control-element for-con-v trolling theiflowof electrons passing throughihe tube-in the manner commonly; employed inordinary vacuum tubes. In. the .Barkhausen. oscillator there is a.pendulum orv to-and-fro motion of the electrons about the gridatthecenter point,

groups; of theseelectrons; being drawn. from "the. cathode toward the:grid. and. after passing. through the gridrreturning again to. it, someof.- these electrons returningto. the vicinity. of the cathode. Theelectronsreturningto the cathode. build up a dynamiclspace chargein:such manner as to control the emission.fromitheicathoder. in

much the same way as a negative'charge on..the gridcontrols theemission: from. thevcathodeof an ordinary vacuum tube. In.conSideringLthe.

Barkhausen. oscillator; it. should be noted that .a.

. negative charge exists inthe' space byvirtue only of the presence oftheelectronsthemselves, since no control electrode is required. Thisphenom.-

enon, it has beeniound, is much more. successful. in producing ultra.high. frequency oscillations. than that employed in the ordinary. vacuumtube wherein controlelectrodes are used, for. the reasonv that thecapacity current to thecontrol electrode in. the ordinary vacuum tube.becomes so.

enormous that the losses due tothis: currentprevent oscillations takingplaceatextremely high.

a certain point is soon reachedbeyond which nofurther increase infrequency may be obtained by increasing the voltage, because of thenecessity for the greater. spacing betweenelectrodes.

A.primary object of the invention is to. makeit.

possible to obtain relatively very high power by means of oscillatorswithout a corresponding decreasein. the limiting frequencies which maybe produced, particularly in the case of. oscillators functioning on,the. Barkhausen and magnetron principles.

An important feature of the present invention is the.-..so1id .type' ofcylindrical plate. electrode used", which has.-anaperture or slottherein for enabling. groups: of electrons to pass through the ,plateelectrode to a positive'charged anode spaced away from the plate andfacing the aperture or slot.

- Although theprinciples underlying the inventionare described withspecial" reference to magnetron and Barkhausen oscillators, it is to bedistinctly understood. that the. invention is not limited thereto, norto the particular arrangement of parts shown, since other organizationsof parts can be used without' departing from the "spiritiandlscopethereof.

Referring to the-drawing: I v Fig. 1 illustrates diagrammatically, theinvention as appliedto a magnetron type of oscillation generator, and

Fig; 2 showsa Barkhausen oscillator system embodying the features of theinvention.

. For the sake of simplicity and in order not to complicatethezdraWing,both figures show cross sectional views-of the oscillator tubes.

Fig." 1 illustrates, in general, an ultra short wave oscillationgenerator'intheform of a magnetron having 'within an envelope l, acylindrical plate electrode 2, a cathode extending alongthe longitudinalaxisof 'the=platecylinder, the whole being surrounded by-ia field willfor producing an intense magnetic field inn-direction parallel to theaxisof the filament. Since the method by which oscillations are producedin magnetronsis well known, and isadequately described in JapanesePatentNo: 7.55255,- granted January 25, 1928, to Kinjiro- Okabe; and 1in my United States- Patents Nos. 2;037-",897"'and 2,0413%, grantedApril 21'and May 26, 1936, respectively, it will not-be describedherein.

- According: to the present invention, the cylindrical plate 2 of themagnetron is provided with a slot 5, and facing thi's slot there isprovided, within the envelope I, an anode ii which is maintained at averyhighpositive potential by source l; wherebyd'uring' the operation ofthe magnetron and' wh'ile oscillations are being produced, those.portions'of the electrons'which approach the. area. of the. slot 5 and.comecwithin'. the electrostatic: fieldz of. the-anode 6 will be drawnto-.

ward the anode 6. In this manner groups or puffs of electrons areemitted through the slot and accelerated toward the anode 6, whichgroups of electrons constitute a fluctuating current having a frequencyequal to the frequency of oscillations being produced by the magnetronoscillator.

Since the magnetic field causes the electrons to take a curved path,anode 6 is made suflicient- 1y large to extend to one side of theaperture so that the electrons do not miss it altogether. If desired,the anode may be positioned on one side of the aperture a suitableamount, as shown in Fig. 2, and not directly opposite the aperture.

Although it is preferred to use a slot in the plate 5, it will be quiteevident that any suitable aperture having appreciable size will functionas well.

As an illustration of the amount of power capable of being obtained bythe oscillator of the invention, let it be assumed that the plate 2 ofthe magnetron oscillator is maintained by source l' at a positivepotential of 2000 volts, and anode 6 at approximately 100,000 voltsrelative to the cathode. If the total plate current in the magnetronoscillator functioning to produce frequencies of the order of 1,000,000kilocycles is approximately 0.5 ampere and the peak emission currentpermitted to escape through the slot in plate 2 is 0.1 ampere, then theR. M. S. value of the current through the slot to anode 6 will beapproximately The efiective or R. M. S. alternating current voltage,available for internal drop and useful output to the output circuitconnected to anode 6, will be 1oo,000 2=35,000 volts If it is assumedthat the anode 6 is 100% efficient then the output will be 0.035 X35,000=1225 watts In practice the anode 6 will be perhaps 40% efficientand provide an output of about 500 watts. The remaining power of about625 watts will be lost in heat at the anode. It will be understood, ofcourse, that the specific values herein mentioned are only given by wayof example, since they happen to be approximately the values obtainableby types of magnetron oscillators commonly used in the field.

The anode circuit may, if desired, be tuned by a condenser 8, one ofwhose plates is connected to a movable slider 9 arranged to glide overthe connection extending from the anode 8 to the source of potential 7.Any suitable utilization circuit, such as an antenna i0, may beconnected to the anode circuit through a transmission line i I, which inturn is shown inductively coupled to the anode circuit by means of astraight wire lead I2. If desired, tuning elements such as tromboneslides 13, M may be inserted in the transmission line circuit for tuningthe line to the desired frequency. Telegraph key I5 is merelyillustrative of any suitable means for modulating the oscillationsproduced.

Since radiation takes place directly from the pulsating electron streammade up of the groups of electrons which are accelerated toward theanode 6, it is preferred to use a reflector l5 instead of thetransmission line antenna output circuit. Thus, by allowing radiation totake place directly from the electron stream there is obtained a sort ofinfra-red lamp which may be used in the focus of the reflector IS, thelatter being designed to reflect the radio frequency waves in much thesame way as a reflector of light. By positioning the tube in thereflector I 5 in any desired manner, advantage may be taken of theposition for maximum radiation, although it will be noted that suchmaximum radiation from the pulsating stream of the electrons Will notordinarily be at right angles to the axis of the tube.

Fig. 2 illustrates the application of the principles of the presentinvention to a Barkhausen oscillator. In this figure, the elements ofthe tube within the envelope are arranged similar to those in Fig. 1except for the provision of a grid [6 which is shown to be positivelycharged by source 1, while the plate 2 is negatively charged by source Hin order to obtain the desired pendulum motion of the electrons. Asshown in the drawing, anode 6 is maintained at a much higher positivepotential than grid [6 relative to the cathode. Portions of theelectrons emanating from the cathode 3 and passing through the grid ltravel out to the vicinity of the plate 2, some of which are subjectedto the electrostatic field from the anode in the same manner as theelectrons of the magnetron oscillator of Fig. 1. In this case also,radiation may be directly obtained from the pulsating electron systemflowing to the anode 6, if desired, or the energy may be amplified inoutput circuit l 1, shown coupled to the anode lead.

From the foregoing it will be quite apparent that the invention isapplicable to various types of oscillators such as the Gill-Morrell typeof oscillator, and oscillators of the ordinary type wherein there isemployed a vacuum tube of small dimensions capable of producing veryhigh frequency oscillations in the same manner as low frequencyoscillations are produced with the ordinary vacuum tube.

What is claimed is:

1. An ultra high frequency oscillation generator comprising a cathode, asubstantially cyiindri cal electrode surrounding said cathode andapertured to permit the passage of electrons therethrough, meansincluding connecting circuits so related to said cathode and saidelectrode as to constitute therewith a self-contained oscillator, ananode located outside said apertured electrode for receiving theelectrons passing therethrough, and means including a source ofpotential for applying a positive potential to said anode for attractingelectrons from said cathode toward said apertured electrode, wherebyelectrons escaping through said apertured electrode impinge on saidanode.

2. An ultra high frequency oscillation generator comprising a cathode,an imperforate, substantially cylindrical plate electrode having anaperture in the side thereof surrounding said cathode, means forattracting electrons from said cathode toward said plate electrode, andan anode located outside said plate electrode and facing said aperture,means for producing electron oscillations within the hollow area of saidplate electrode, and means for supplying a high positive potential tosaid anode with respect to said cathode for producing an electrostaticfield in the vicinity of said aperture, whereby electrons escapingtherethrough impinge on said anode.

3. An ultra high frequency oscillation generator metallic substantiallycylindrical plate electrode I outside saidv cylinder but within saidenvelope surrounding said cathode and having a slot running through theentire length thereof, an anode facing said slot whereby electronsescaping therethrough impinge onsaid anode, means for producing electronoscillations within the hol low area of said cylindrical plate electrodeincluding a source of potential for applying a positive potential onsaid plate and a relatively very high positive potential on saidanodewith respect tosaidcathode. 1

4. An ultra high frequency oscillator comprising an envelope havingwithin it a cathodeand a substantially cylindrical plate electrodesurrounding said cathode, said plate electrode having an aperture in theside thereof for the escape therethrough of electrons emanating fromvsaid cathode, and an anode located within said envelope and outsidesaidplate electrode and directly-in'line with said aperture and cathode forreceiving said electrons, means for maintaining said cylindrical plateata positive potential and. said anode at a much higher positivepotential N relative to said cathode, and a field coil surrounding saidenvelope for influencing the direction of travel of said electrons.

5. An electron discharge device comprising a cathode, a grid, and acylindricalplate, means for supplying said grid with a high positivepotential and said plate with a much lower potential relative to saidcathode, said plate having an aperture for the escape of electronstherethrough emanating from said cathode and passing through said grid,and an anode facing said aperture for receiving said electrons aftertheir escape through the aperture of said plate, and means formaintaining said anode at a positive potential which is much higher thanthat applied to said grid.

"6. In combination, an ultra high frequency oscillation generatorcomprising a cathode, an imperforate, substantially cylindrical plateelectrode surrounding said cathode, said plate electrode having anaperture in the side thereof, means for attracting electrons from saidcathode toward said plate electrode, means for producing oscillationswithin the hollow area of said cylindrical plate electrode, and an anodelocated outside said plate electrode and facing said aperture wherebytially cylindrical plate electrode surrounding said cathodesubstantially completely, said cylindrical plate having an aperture inthe side thereof, means for attracting electrons from said cathodetoward said plate electrode, means for producing electron oscillationswithin the hollow area of said plate electrode, and an anode locatedoutside said plate electrode and facing said aperture, said anodebeingpositively biased whereby electrons escaping through said apertureimpinge on said anode.

8. An ultra high frequency oscillation generator comprising a cathode, ahollow, imperforate plate electrode substantially completely surroundinga portion of said cathode, said plate having an aperture in the sidethereof, means including a source of potential for attracting electronsfrom said cathode toward said plate electrode, means for producingelectron oscillations within thehollow areaof said plate electrode, ananode located outside said plate electrode and facing said:aperture,'and a connection from said anode to a positive terminal ofsaid source whereby electrons escaping through said aperture arecaused'to impinge on said anode. i

9. An electron discharge tube circuit comprising an electron emittingmeans, an anode, means relatively to said emitting means, and means forvcausing an intermittent fiow of electrons from said emitting means tosaid'anode comprising additional electrodes and connecting circuitssorelated to said emitting means as to constitute therewith a brakingfield type of oscillator, said positive potential being such that theoscillatory energy available between said anode and said emitting meansis large as compared with the braking field oscillatory energy. j I

10. An electron discharge tube circuit comprising, a'n electron emittingmeans, an anode separated from said emitting means only by etheric,

space, means for impressing a positive potential on said anoderelatively to said emitting means,

and means for causing an intermittent flow of electrons from saidemitting means to said anode comprising additional electrodes andconnecting circuits so relatedto said emitting means as to anode andsaid emitting means is large'as compared with the braking fieldoscillator energy.

11. An electron discharge tube circuit comprising, an electron emittingmeans, means-for causing an intermittent flow of electrons from saidemitting means comprising additional electrodes and connecting circuitsso related to said emitting means as to constitute therewith a brakingfield type of oscillator, an anode, and means for impressing a positivepotential on said anode relatively to said braking field oscillatorelectrodes, said positive potential being such that theoscillatoryenergy available between said anode and said emitting meansis large as compared with the braking field oscillator energy.

12. An electron discharge tube circuit comprising an electron emittingmeans, an anode, means for impressing a positive potential on said anoderelatively to said emitting means, and means for causing an intermittentflow of electrons from said emitting means to said anode comprisingadditional electrodes and connecting circuits so related to saidemitting meansas to constitute therewith a self-contained positive gridtriode oscillator, said positive potential being large asmeans forperiodically impulsively energizing said 1 tuned circuit from saidpotential impressing means comprising additional electrodes and circuitmeans so related to said cathode as'to constitute therewith aself-contained positive grid triode oscillator, said positive potentialbeing large as compared with the potentials used in said self-containedoscillator.

14. The oscillator circuit as specified in claim 13 in which saidenergizing means comprises said additional electrodes and circuit meansadapted to cooperate with said cathode to constitute therewith a brakingfield type of oscillator circuit.

15. An electron discharge tube circuit compris- 5 ing, an electronemitting means, an anode separated from said emitting means only byetheric space, means for impressing a positive potential on said anoderelatively to said emitting means, and means for causing an intermittentflow of m electrons from said emitting means to said anode comprisingadditional electrodes and connecting circuits so related to saidemitting means as to constitute therewith a self-contained positive gridtriode oscillator, said positive potential being 15 large as comparedwith the potentials used in said self-contained oscillator.

16. An electron discharge tube circuit comprising, an electron emittingmeans, an anode, means for causing an intermittent flow of electronsfrom 30 said emitting means to said anode comprising additionalelectrodes and connecting circuits so related to said emitting means asto constitute therewith a self-contained positive grid triodeoscillator, and means for impressing a positive potential on said anoderelatively to the intermittent electron flow means constituted by saidoscillator electrodes, said positive potential being large as comparedwith the potentials used in said self-contained oscillator.

17. The oscillator circuit specified in claim 13 in which said tunedcircuit is adjusted so that the whole circuit including said tunedcircuit and the interelectrode capacitances of the electron dischargetube is tuned to the frequency of said periodic impulses.

18. The oscillator circuit specified in claim 13, in which saidenergizing means comprises said additional electrodes and circuit meansso related to said cathode as to constitute therewith a braking fieldoscillator circuit and in which said tuned circuit is adjusted so thatthe whole circuit including said tuned circuit and the interelectrodecapacitances of the electron discharge tube is tuned to the frequency ofsaid periodic impulses.

CLARENCE W. HANSELL.

